diff --git a/src/App.svelte b/src/App.svelte
index a880ee2..ea9c222 100644
--- a/src/App.svelte
+++ b/src/App.svelte
@@ -3,15 +3,40 @@
     import viteLogo from "/vite.svg";
     import { navigate } from "./lib/common";
     import { currentView } from "./lib/store";
-    import FatPercentage from "./lib/FatPercentage.svelte";
+    import ArmyFatPercentage from "./lib/ArmyFatPercentage.svelte";
+    import NavyFatPercentage from "./lib/NavyFatPercentage.svelte";
+    import OneRepMax from "./lib/OneRepMax.svelte";
 </script>
 
-{#if $currentView === "fatcalc"}
-    <FatPercentage />
+{#if $currentView === "armyfatcalc"}
+    <ArmyFatPercentage />
+{/if}
+{#if $currentView === "navyfatcalc"}
+    <NavyFatPercentage />
+{/if}
+{#if $currentView === "onerepmax"}
+    <OneRepMax />
 {/if}
 {#if $currentView === "start"}
-    <button onclick={() => navigate("fatcalc")}>Kroppsfettkalkylator</button>
+    <main>
+        <nav>
+            <button onclick={() => navigate("armyfatcalc")}
+                >Kroppsfettkalkylator, Army</button
+            >
+            <button onclick={() => navigate("navyfatcalc")}
+                >Kroppsfettkalkylator, Navy</button
+            >
+            <button onclick={() => navigate("onerepmax")}>1RM-kalkylator</button
+            >
+        </nav>
+    </main>
 {/if}
 
 <style>
+    nav {
+        display: grid;
+        grid-template: subgrid / subgrid;
+        grid-column: 2 / 2;
+        grid-row: 2 / 6;
+    }
 </style>
diff --git a/src/app.css b/src/app.css
index 92455a0..395a0a3 100644
--- a/src/app.css
+++ b/src/app.css
@@ -17,6 +17,19 @@ body {
     margin: 0;
 }
 
+button {
+    border: 5px solid crimson;
+    background-color: transparent;
+    border-radius: 0;
+    color: inherit;
+
+    &:hover,
+    &:focus {
+        border-color: #fff;
+        background-color: rgba(255, 255, 255, 0.1);
+    }
+}
+
 header {
     background-color: crimson;
 }
@@ -26,4 +39,65 @@ h2,
 h2 {
     font-size: 1em;
     margin: 0;
+    text-wrap: balance;
+}
+
+main {
+    min-width: 100vw;
+    min-height: 100vh;
+    display: grid;
+    gap: 1em;
+    padding: 1em;
+    box-sizing: border-box;
+    grid-template-columns: repeat(3, 1fr);
+    grid-template-rows: repeat(7, 1fr);
+}
+
+output {
+    background: rgba(0, 0, 0, 0.25);
+    display: grid;
+    grid-column: 1 / 4;
+    grid-row: 2 / 4;
+    grid-template: subgrid / subgrid;
+    font-size: 2em;
+
+    > span {
+        grid-column: 1 / 6;
+        grid-row: 1 / 2;
+        text-align: right;
+
+        &::before {
+            content: "=";
+            color: #888;
+        }
+
+        &::after {
+            content: "%";
+            color: #888;
+        }
+    }
+}
+
+form {
+    background: rgba(255, 255, 255, 0.25);
+    display: grid;
+    grid-column: 1 / 4;
+    grid-row: 4 / 8;
+    grid-template: subgrid / subgrid;
+}
+
+input {
+    max-width: 4em;
+    display: block;
+}
+
+header {
+    display: grid;
+    grid-column: 1 / 4;
+    grid-row: 1 / 1;
+    grid-template: subgrid / subgrid;
+}
+
+h1 {
+    grid-column: 2 / 4;
 }
diff --git a/src/lib/FatPercentage.svelte b/src/lib/ArmyFatPercentage.svelte
similarity index 72%
rename from src/lib/FatPercentage.svelte
rename to src/lib/ArmyFatPercentage.svelte
index 12e264e..c85056d 100644
--- a/src/lib/FatPercentage.svelte
+++ b/src/lib/ArmyFatPercentage.svelte
@@ -43,7 +43,7 @@
         <span>
             <button onclick={() => navigate("start")}>Tillbaka</button>
         </span>
-        <h1>Kroppsfettkalkylator</h1>
+        <h1>Kroppsfettkalkylator, Army</h1>
     </header>
     <output>
         {#if fatPercentage > 0}
@@ -123,68 +123,8 @@
 </main>
 
 <style>
-    main {
-        min-width: 100vw;
-        min-height: 100vh;
-        display: grid;
-        gap: 1em;
-        padding: 1em;
-        box-sizing: border-box;
-        grid-template-columns: repeat(3, 1fr);
-        grid-template-rows: repeat(7, 1fr);
-    }
-
-    output {
-        background: rgba(0, 0, 0, 0.25);
-        display: grid;
-        grid-column: 1 / 4;
-        grid-row: 2 / 4;
-        grid-template-columns: subgrid;
-        font-size: 2em;
-
-        > span {
-            grid-column: 1 / 6;
-            grid-row: 1 / 2;
-            text-align: right;
-
-            &::before {
-                content: "=";
-                color: #888;
-            }
-
-            &::after {
-                content: "%";
-                color: #888;
-            }
-        }
-    }
-
-    form {
-        background: rgba(255, 255, 255, 0.25);
-        display: grid;
-        grid-column: 1 / 4;
-        grid-row: 4 / 8;
-        grid-template-columns: subgrid;
-    }
-
     .gender {
         grid-column: 1 / 2;
         grid-row: 1 / 4;
     }
-
-    input {
-        max-width: 4em;
-        display: block;
-    }
-
-    header {
-        display: grid;
-        grid-column: 1 / 4;
-        grid-row: 1 / 1;
-        grid-template-columns: subgrid;
-    }
-
-    h1 {
-        grid-column: 2 / 4;
-    }
 </style>
diff --git a/src/lib/NavyFatPercentage.svelte b/src/lib/NavyFatPercentage.svelte
new file mode 100644
index 0000000..ff2a9ff
--- /dev/null
+++ b/src/lib/NavyFatPercentage.svelte
@@ -0,0 +1,136 @@
+<script lang="ts">
+    import { navigate } from "./common";
+
+    let fatPercentage = $state(0);
+    let gender = $state("male");
+    let height = $state(null);
+    let waist = $state(null);
+    let neck = $state(null);
+    let hips = $state(null);
+
+    // https://www.omnicalculator.com/health/navy-body-fat
+
+    const male = (waist: number, neck: number, height: number) =>
+        495 /
+            (1.0324 -
+                0.19077 * Math.log10(waist - neck) +
+                0.15456 * Math.log10(height)) -
+        450;
+
+    const female = (
+        waist: number,
+        neck: number,
+        hips: number,
+        height: number,
+    ) =>
+        495 /
+            (1.29579 -
+                0.35004 * Math.log10(waist + hips - neck) +
+                0.221 * Math.log10(height)) -
+        450;
+
+    const calculate = () => {
+        if (gender == "male") {
+            if (!waist || !neck || !height) {
+                return;
+            }
+            fatPercentage = male(waist, neck, height);
+        } else {
+            if (!waist || !neck || !height || !hips) {
+                return;
+            }
+            fatPercentage = female(waist, neck, hips, height);
+        }
+    };
+</script>
+
+<main>
+    <header>
+        <span>
+            <button onclick={() => navigate("start")}>Tillbaka</button>
+        </span>
+        <h1>Kroppsfettkalkylator, Navy</h1>
+    </header>
+    <output>
+        {#if fatPercentage > 0}
+            <span>{Math.round(fatPercentage * 100) / 100}</span>
+        {/if}
+    </output>
+    <form>
+        <div class="gender">
+            <label>
+                Man
+                <input
+                    bind:group={gender}
+                    type="radio"
+                    name="gender"
+                    value="male"
+                    id="male"
+                />
+            </label>
+            <label>
+                Kvinna
+                <input
+                    bind:group={gender}
+                    type="radio"
+                    name="gender"
+                    value="female"
+                    id="female"
+                />
+            </label>
+        </div>
+        <label>
+            Kroppslängd
+            <input
+                onchange={() => calculate()}
+                bind:value={height}
+                type="number"
+                id="height"
+                name="height"
+                size="5"
+            />
+        </label>
+        <label>
+            Midja
+            <input
+                onchange={() => calculate()}
+                type="number"
+                bind:value={waist}
+                id="waist"
+                name="waist"
+                size="5"
+            />
+        </label>
+        {#if gender == "female"}
+            <label>
+                Höft
+                <input
+                    onchange={() => calculate()}
+                    type="number"
+                    bind:value={hips}
+                    id="hips"
+                    name="hips"
+                    size="5"
+                />
+            </label>
+        {/if}
+        <label>
+            Hals
+            <input
+                onchange={() => calculate()}
+                type="number"
+                bind:value={neck}
+                id="neck"
+                name="neck"
+                size="5"
+            />
+        </label>
+    </form>
+</main>
+
+<style>
+    .gender {
+        grid-column: 1 / 2;
+        grid-row: 1 / 4;
+    }
+</style>
diff --git a/src/lib/OneRepMax.svelte b/src/lib/OneRepMax.svelte
new file mode 100644
index 0000000..43aba57
--- /dev/null
+++ b/src/lib/OneRepMax.svelte
@@ -0,0 +1,56 @@
+<script lang="ts">
+    import { navigate } from "./common";
+
+    let oneRepMax = $state(0);
+    let reps = $state(null);
+    let weight = $state(null);
+
+    // https://www.athlegan.com/calculate-1rm
+
+    const calculate = () => {
+        if (weight && reps) {
+            oneRepMax = weight / (1.0278 - 0.0278 * reps);
+        }
+    };
+</script>
+
+<main>
+    <header>
+        <span>
+            <button onclick={() => navigate("start")}>Tillbaka</button>
+        </span>
+        <h1>1RM</h1>
+    </header>
+    <output>
+        {#if oneRepMax > 0}
+            <span>{Math.round(oneRepMax * 100) / 100}</span>
+        {/if}
+    </output>
+    <form>
+        <label>
+            Reps
+            <input
+                onchange={() => calculate()}
+                bind:value={reps}
+                type="number"
+                id="reps"
+                name="reps"
+                size="5"
+            />
+        </label>
+        <label>
+            Vikt
+            <input
+                onchange={() => calculate()}
+                type="number"
+                bind:value={weight}
+                id="weight"
+                name="weight"
+                size="5"
+            />
+        </label>
+    </form>
+</main>
+
+<style>
+</style>
diff --git a/src/lib/common.ts b/src/lib/common.ts
index 9085240..74a557c 100644
--- a/src/lib/common.ts
+++ b/src/lib/common.ts
@@ -1,4 +1,5 @@
 import { currentView } from "./store";
 
-export const navigate = (page: "start" | "fatcalc") =>
-  currentView.update((_) => page);
+export const navigate = (
+  page: "start" | "armyfatcalc" | "navyfatcalc" | "onerepmax",
+) => currentView.update((_) => page);